Event-Driven Simulation of the Dynamics of Hard Ellipsoids

TL;DR

This paper presents a new event-driven simulation algorithm for hard ellipsoids, analyzing their translational and rotational dynamics, revealing decoupling phenomena and glassy behavior near potential pre-nematic transitions.

Contribution

A novel geometric-distance-based algorithm for simulating arbitrary-shaped rigid bodies, applied to ellipsoids to study their complex dynamical behavior.

Findings

Decoupling of translational and rotational diffusion lines.

Glassy dynamics observed at high packing fractions and aspect ratios.

Stretching of orientational correlators indicating complex relaxation processes.

Abstract

We introduce a novel algorithm to perform event-driven simulations of hard rigid bodies of arbitrary shape, that relies on the evaluation of the geometric distance. In the case of a monodisperse system of uniaxial hard ellipsoids,we perform molecular dynamics simulations varying the aspect-ratio X0 and the packing fraction phi. We evaluate the translational Dtrans and the rotational Drot diffusion coefficient and the associated isodiffusivity lines in the phi-X0 plane. We observe a decoupling of the translational and rotational dynamics which generates an almost perpendicular crossing of the Dtrans and Drot isodiffusivity lines. While the self intermediate scattering function exhibits stretched relaxation, i.e. glassy dynamics, only for large phi and X0 about equals to 1, the second order orientational correlator C2(t) shows stretching only for large and small X0 values. We discuss these findings in the context of a possible pre-nematic order driven glass transition.